<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-grid-2/">
<style>
.item {
  inline-size: 40px;
  box-sizing: border-box;
  border: solid 5px hotpink;
  line-height: 0;
  margin-block-start: 3px;
  margin-block-end: 5px;
}
.small {
  width: 30px;
  height: 30px;
  border: solid 5px cyan;
}
.first {
  align-self: baseline;
}
.last {
  align-self: last baseline;
}
span {
  width: 20px;
  height: 20px;
  box-sizing: border-box;
  border: solid 5px orange;
  display: inline-block;
}
</style>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/check-layout-th.js"></script>
<body onload="checkLayout('.item')">

<div style="writing-mode: vertical-rl; width: 600px; position: relative; display: grid; grid-template: 150px 150px 150px / 100px 100px 100px 100px;">
  <div style="display: grid;
              gap: 10px;
              grid-column: 1 / span 2;
              grid-row: 1 / span 3;
              grid-template: subgrid / subgrid;
              margin-block-start: 5px; margin-block-end: 10px;
              border: solid black 5px;
              padding-block-start: 10px; padding-block-end: 20px;">
    <div style="display: grid;
                gap: 20px;
                grid-column: 1 / span 2;
                grid-row: 1 / span 2;
                grid-template: subgrid / subgrid;
                margin-block-start: 3px; margin-block-end: 7px;
                border: solid black 5px;
                padding-block-start: 5px; padding-block-end: 10px;">
      <div data-offset-x="514" class="item first">
        <span></span><br><span></span>
      </div>
      <div data-offset-x="465" class="item last">
        <span></span><br><span></span>
      </div>
      <div data-offset-x="387" class="item first">
        <span></span><br><span></span>
      </div>
      <div data-offset-x="332" class="item last">
        <span></span><br><span></span>
      </div>
    </div>
    <div data-offset-x="242" class="item first">
      <span></span><br><span></span>
    </div>
    <div data-offset-x="190" class="item last">
      <span></span><br><span></span>
    </div>
  </div>
  <div data-offset-x="534" class="item small first"></div>
  <div data-offset-x="465" class="item small last"></div>
  <div data-offset-x="407" class="item small first"></div>
  <div data-offset-x="332" class="item small last"></div>
  <div data-offset-x="262" class="item small first"></div>
  <div data-offset-x="190" class="item small last"></div>
</div>
